chemistry final Flashcards
1
Q
what is pressure
A
the force exerted by molecules hitting the walls of a container
2
Q
whats the formula for pressure
A
P=F/a
3
Q
whats the ideal gas law formula
A
PV=nRT
4
Q
How do molecules move in a gas sampl
A
different speeds, mostly at a medium speed, if theyre heavier theyre slower, lighter is faster, they move in straight lines
5
Q
whats an elastic collision
A
molecules bounce off of eachother they change directions but don’t lose or gain energy
6
Q
whats the collision theory
A
that collisions have to happen for a reaction to occur, they give the minimum energy required, orientation matters
7
Q
how should a number of molecule x speed graph look
A
all the curves have to have the same area underneath to show the same number of molecules, colder will have a higher peak earlier and hotter will have a lower peak later on
8
Q
whats the formula for average rate of rxn
A
change in concentration/change in time, always positive
9
Q
whats an instantaneous rate
A
the rate at 1 specific point
10
Q
how will an instantaneous rate look on a conc. x time graph
A
it will be tangent to the curve, steeper is faster
11
Q
what does a relative rate mean
A
if there is a reaction with different coefficients, they have to match up to show the rates, if it was 2NH3 -> N2 + 3H2 the rate of production for H2 = 3 x the rate of production of N2 and then rate of consumption would be the same because it has to use up all the product
12
Q
what is a half life
A
the time for a concentration to decrease by half
13
Q
whats the experimental rate equation
A
rate = k[A]^m[B]^n
14
Q
is time included in the rate equation
A
no
15
Q
what do the exponents m and n mean in the rate equation
A
they show the order of rxn for the different concentrations, how sensitive that solution is to the rate
16
Q
how do you find the units for k
A
you have rate unit which is mol/Ltime and then you have the concentrations on the other side so you have to make k cancel things out to get the units for rate
17
Q
how do you find the order of rxns
A
you compare different trials where one solution has the same concentration, then you line them up and cancel things out to get one of the orders of reaction
18
Q
how do you find k
A
you do the rate divided by the concentrations with their order of reactions as exponents
19
Q
how does a conc. x time graph look for all the different orders of rxn
A
n=2 will be the slowest and n=0 will be the fastest because as conc. is decreasing the higher the exponent is the smaller the number for the rate will be so less concentration will be used up
20
Q
what is an integrated rate law
A
it relates concentration remaining to the change in time
21
Q
whats the formula for a rate of 0th order
A
rate = k
22
Q
what does the rate of a 0th order depend on
A
its always the same, doesn’t depend on concentration
23
Q
whats the integrated rate law for 0th order
A
[A]t = -kt + [A]0
24
Q
describe the graph of 0th order
A
k is the slope, it will be linear
25
whats the formula for a 1st order rate
rate = k[A]
26
what does the rate of 1st order depend on
the concentration, fast when concentration is bigger
27
whats the integrated rate law of 1st order
ln[A]t= -kt + ln[A]0
28
what does the graph of a first order reaction look like
it will be an exponential decay but linear if it were ln[] x time
29
whats the formula for a 2nd order rate
rate = k[]^2
30
what does the 2nd order rate depend on
the concentration , bigger concenttration is faster
31
whats the integrated rate law for 2nd order
a/[]t = kt + 1/[]0
32
what does the 2nd order graphs look like
not linear unless 1/[] x time
33
what is a transition state
where bonds are partially formed and broken its very unstable
34
what does an endothermic vs exothermic graph look like
exo ends lower than it started, endo ends higher than it started
35
what is arrhenius formula
rate constant k = Ae^(-Ea/RT)
36
what has to be true about the energy of a collision and activation energy for a rxn to occur
the energy of a collision has to be bigger than the activation energy
37
what are three factors that affect the rate
- higher concentration means its more likely for a collision to occur
- a higher temp means moving faster which means more collisions
- a larger activation energy is slowe, smaller is faster
38
what is a reaction mechanism
the steps and species in a collision
39
whats an elementary step and what are its components
1 single collision event, exo or endo, has 1 transition state, an Ea
40
what is the slowest elementary step
the rate determining step
41
is activation energy larger when breaking or forming bonds
breaking
42
what is an intermediate species
a species formed by an elementary step then consumed by another
43
what does a catalyst do
increase the rate by lower activation energyh
44
how does a catalyst appear in a rxN
consumed by one elementary step then reformed by another
45
how do you know when a rxn has gone to completion
all possible bonds are formed, limiting reagent is used up
46
what happens to q at equilibirium
it stops changing and becomes k
47
whats the formula for q/k
concentration or pressure of products with exponents of coefficients/ concentration or pressure of reactants with exponents of coeeficients
48
what is never included in k or q
liquids and solids
49
whats the difference between q and k
q can be calculated at any time, k is at eq
50
what are ice tables for
to find k or missing concentrations
51
what does it mean is q>k
there are a lot of products so it has to favour the reverse rxn
52
what does it mean if q
there is a lot of reactant so it has to favour fwd rxn
53
what does it mean if k>>1
theres a lot of products
54
what does it mean if k<<1
theres a lot of reactants
55
what is LeChateliers principle
a system at equilibrium counteracts any changes by favouring the forward or reverse rxn
56
if you add water to a reaction where one has a bigger coefficient will it favor fwd or rev rxn
it will favor the direction with the bigger coefficient because the water will dilute the more concentrated solution
57
how do you find the new k if you multiply a rxn by n
you do (old k)^n
58
how do you find the new k if you flip a rxn
you do 1/(old k)
59
how do you find the new k if you add rxns
you multiply the two ks
60
what is the bronsted lowry definition of acids and bases
acid are proton donors bases are proton acceptors
61
what does the strength of an acid/base mean
the stronger the acid/base the more willing it is to accept/donate a proton, it will go to completion
62
what do the concentrations say about acids vs bases
more h30 than oh = acid
equal h30 and oh= neutral
more oh than h30= basic
63
what is autoionization of water
its two waters colliding to make h30 and oh
64
what is kw
1.0 x 10^-14
kw= kaxkb
65
how do you find ph/poh/pk
-log[h30], -log[oh], -log[k]
66
how do you find [h30], [oh], [k]
10^-ph,poh,pk
67
what does adding a salt to a solution do
salt dissolved to form cation and anion, and those can act as acids or basees to form h30 or oh
68
is breaking or forming bonds exo or end
exo- forming bonds
endo- breaking bonds
69
what are polyprotic acids
they can give more than 1 H in a successive manor
70
what is approximation method
when finding k if kx1000 < []0 then you can change the denominator of a k equation to just x instead of 10-x
71
what happens when we add a strong base to a solution with an acid
the acid concentration decreases and the conjugate baseincreases
72
what is the equivalence point
when exactly enough base is added to react with all the acid
73
what is the end point
its past the equivalence point when we see the visual change in color
74
what is the half equivalence point
when have of the acid has reacted, so half acid, half base
75
what happens to ph at 1/2 eq pt
ph=pka
76
how do we find the concentration of an unknown species in a titration
we find the volume of the base added at the equivalence point
77
how do we find the identity of an unknown acid
we find the volume at the half equivalence point (volume at eq/2) then use that to find ph then ph=pka then ka =10^-pka
78
what does it mean if two curves have the same ph at half eq point
theyre the same acid but different mols
79
what affects the volume of OH- required to reach eq in a titration
the moles not the strength
80
what controls the color of an indicator
the base acid ratio
81
if the acid base ratio is 1 what does it mean and when does it happen
its a mix of color, it happens when ph=pk
82
if the acid base ratio is less than 1 what does it mean and when does it happen
the dominant color will be controled by the acid it happens when theres a lot of h30 so a lower ph
83
if the acid base ratio is bigger than 1 what does it mean and when does it happen
the dominant color will be controled by the base and happens when theres a lot of oh so a higher ph
84
how do we choose the indicator pk
it should be the same as the ph at eq
85
what does a buffer do
it resists change in ph
86
what are the requirements for a buffer
a solution with similar amounts of HA and A in equilibirum
87
how much can the HA and A differ by in a buffer
btwn 0.1 and 10
88
what will the concentration ratio look like for a buffer
moles of base/moles of acid since they are in the same solution
89
whats the formula for ph of a buffer
ph= pka + log[A-]/[HA]
90
whats the approximation in a buffer
that the concntrations at equilibrium = the intitial concentrations
91
how do you prepare a buffer
1. choose an acid/base based on pka (the pka should be close to the target ph)
2. use the acid base ratio to adjust to the target oh
92
whats method 1 of a buffer
to mix HA and salt of A-
93
whats method 2 of a buffer
the partial titration of HA and NaOH to make A-
94
why cana buffer withstand the addition of acid/base
it has something to react with the added and neutralize it
95
what is the solubility of a salt
the max amount of salt that can be dissolved to produce a saturated solution at equilibrium
96
what does the reaction for a soluble salt look like
the salt dissolved completely to a cation and anion
97
what does the reaction for a partially soluble salt look like
the salt dissolves into cation and anion but with eq arrows
98
what is the k expression for a salt
ksp= [cation]^m[anion]^n
99
what does ksp mean
the solubility product
100
is the salt included in the k expression
no
101
how do you figure out if a salt rxn is acidic or basic
look at what is produced and if they have further rxns then they will produce either oh or h30
102
when you add an acid to the dissolution what happens
it favors the dissolution because it will react with the base and go more to completion so lowering the concentration of the base
103
how can we favour the dissolution of a salt
add an acid to remove oh, change the temp, add water to decrease the concentrations
104
what does internal energy contain
potential and kinetic energy
105
what are reactants and products in thermochem
the system, so they have internal energy
106
whats the formula for the change in internal energy of the system in relation to product and reactants
Us= Up-Ur
107
whats the formula for change in internal energy
Us= heat + work
108
What are the signs for system losing/gaining energy
a system losing energy is -
a system gaining energy is +
109
what are the two types of work
electrical and mechanical
110
what is electrical work
moving electrons- redox
111
what is mechanical work
pressure-volume
112
where does pressure volume work come from
the changes in volume from production and consumption of gases
113
what does it mean if the change in volume is positive
its a volume increase, expansion, so it is work done by the system, w is negative since w=-pv so the system is losing energy
114
what does it mean if the change in volume is negative
its decreasing, so compression, the work is done on the system by the surrounding and is positive since w= -p(-v) so the system is gaining energy
115
what is heat
q
116
whats the expression comparinng heat of a rxn and heat of a surrounding
qrxn= -q surrounding
117
what is heat capacity
the j required to increase 1g of solution by 1 degree
118
what is enthalpy
the heat involved when a rxn is under constant pressure
119
what is enthalpy represented by
H
120
is H is - what does that mean, and what if +
- means endo, + means exo
121
what is hess's law
finding the heat of an overall rxn
122
how do you find the heat of an overall rxn
add up each individual heat
123
if youre given a H of formation but its a decomposition what do you do
make it -
124
what are the three endothermic reactions
solid -> liquid, liquid-> gas, solid-> gas
125
what are the two exothermic reactions
liquid-> solid, gas-> liquid
126
what does it mean for something to be spontaneous
it doesnt need continuous external assistance, maybe just a jump start
127
is spontaneous or non spontaneous negative
spon = -, non spon = +
128
what does it mean for something to be non spontaneoud
it needs continuous external assistance
129
if the fwd rxn is spon what is the rev
non spon
130
what is gibbs free energy
a measure of energy G
131
how does gibbs free energy relate to spontaneity
G <0 = spontaneous
G> 0 = non spontaneous
G=0 = equilibirum
132
does changing temp affect gibbs free energy
yes
133
whats the formula for gibbs free energy
G= Hrxn- TSrxn
134
what is entropy
a measure of disorder in a system, dispersal of energy
135
what is the third law of thermodynamics
when T= 0k S=0, as temperature heats up the molecules spread and disorder increases
136
whats the 2nd law of thermodynamics
a spontaneous process results in an increase of entropy
137
whats entropy represented by
s
138
how to tell spontaneity by entropy
s > 0 = spontaneous
s < 0 = non spontaneous
s=0 = in equilibirum
139
what is molar solubility
how many moles can dissolve per litre
140
how does physical state affect entropy
solid is the most ordered then liquid and gas is the most disordered
141
how does number of particles affect entropy
the more particles the more disorder
142
how does the complexity and size of a molecule affect entropy
the more complex the more rotations and vibrations possible so more disorder
143
whats a major factor affecting entropy and a less important one
major is number of particles, least important is complexity/size
144
if q>k how does that affect spontaneity
g>0 so non spontaneous
145
if q
g<0 so spontaneous
146
what is a redox rxn
a rxn that has a half reduction rxn and half oxidation rxn
147
what is a reduction
gain of electron
148
what is oxidation
loss of electron
149
how do you balance a redox equation
1. split it into a reduction and oxidation equation
2. balance the non O and H first
3. Balance O by adding h20
4. Balance H by adding H
5. balance the charges by adding e-
6. put them together and cancel things out
150
what is reduction potential
Ered, the bigger the reduction potential that more they will accept e-s
151
what is oxidation potential
Eox = -Ered
152
what does a +Ecell mean
that the e- transfer is desirable and spontaneous
153
what does a -Ecell mean
the e- transfer is non spontaneous and not favourable
154
whats the difference between E◦cell and Ecell
E◦cell is under standard conditions, Ecell is under experimental conditions
155
What the formula for E◦cell in relation to E◦red and E◦ox
E◦cell=E◦red + E◦ox
156
what is a direct e- transfer
lots of heat and no electrical work
157
what is an indirect e- transfer
less heat and electrical work
158
what direction is the e- flow in indirect e- transfer
anode to cathode
159
what does a galvanic/voltaic cell do
turn chemical energy to electrical energy
160
is galvanic/voltaic spontaneous
yes
161
what is a galvanic cell
it is two half cells, one where oxidation happens and one where reduction happens
162
where does oxidation happen and is it positive or negative
the anode which is negative
163
where does reduction happen and is it positive or negative
the cathode which is positive
164
what does a salt bridge do
it adds + ions to the cathode side which is gaining electrons and it adds - ions to the anode side which is losing electrons, to keep the charge neutral
165
what happens to indirect e- transfer that is non spontaneous
the e- flow is from cathode to anode, and the cathode becomes - and the anode is +
166
what are example of non spontaneous electron transfer
electroplating, electrolysis
167
what happens at the anode
e- are produced by oxidation
168
what happens at the cathode
its where e- are going to be consumed by reduction
169
what is the oxidizing agent
what allows species to be oxidized but it gets reduced
170
what is the reducing agent
what allows species to be reduced but gets oxidized
171
what is cell notation
1 line describing the rxn in the galvanic cell
172
whats the format for cell notation
anode|anode(oxidized) || cathode(reduced)|cathode
173
what does one line separation mean in cell notation
separation of different physical states
174
what does a double line separation mean in cell notation
its represents the salt bridge
175
what is an inert electrode
a solid conductor to provide a surface for e- transfer, used when theres not solid in the rxn
176
how do you use inert electrodes in cell notation
if a rxn doesn't have a solid you put it on the side that needs a solid
177
what can you use as an inert electrode
pt
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